Transposition of the great arteries (TGA) is a congenital heart defect in which the great arteries - the aorta and pulmonary artery (PA) - are transposed across the ventricular septum and arise from the discordant ventricular chambers (ventricular-arterial discordance). It presents with two distinct anatomical subtypes, each with distinct physiologies: dextro-transposition (d-TGA) and levo-transposition (l-TGA), also known as congenitally corrected TGA (ccTGA). In d-TGA, the atria are connected to the appropriate ventricular chambers. However, the aorta arises from the right ventricle (RV) and the PA from the left ventricle, resulting in parallel circulations and inadequate systemic oxygenation [1]. Today, surgical correction is performed during the neonatal period to restore in-series circulation through the arterial switch operation (ASO) [2].

In contrast, l-TGA is characterized by atria and great arteries connections to the discordant chambers (right atria-left ventricle-pulmonary artery and left atria-right ventricle-aorta), so-called atrioventricular and ventriculoarterial discordance or double discordance. Here, the circulations are in series (non-cyanotic) but with a disadvantaged systemic right ventricle. Although individuals with l-TGA often reach adulthood without requiring surgical intervention, they are at risk of experiencing long-term complications, including heart failure and arrhythmias, including complete heart block [3,4].

The surgical management of d-TGA has evolved significantly over the decades. Initially, the atrial switch procedures—Mustard or Senning operations—were the mainstay for treating d-TGA, redirecting blood flow at the atrial level [5,6]. However, the ASO eventually replaced these techniques, restoring the normal anatomical configuration and becoming the standard of care due to its superior long-term outcomes [7,8].